What if there was an easy way to take thecarbon dioxide from coal power smokestacks and turn it back into a rock thatwou!d sit quietly, deep below the earth's surface? That would get around a keysticking point of current carbon storege schemes, which entail injecting CO2into porous sedimentary rcck formations such as sandstone-that the gas couldeventually escape, seeping back up to the surface and into the atmosphere,heating the planet.
Basalic rock, which makes up part of theearth's crust, could be an alternative to sedimentary structures. Mineralswithin basalt, incuding magnesium, calcium and iron, gradiually react with CO2to form carbonate crystals inside the pores and seams of basalt, entombing thecarbon as a permanent solid. This process, known as enhanced weathering, couldcapture massive amounts of CO2. Engineers ane now trying to tum thisbit of chemistry into practice.
This summner near Wallula, Wash,engineers injected almost 1,000 metric tons of CO2 into layeredbasalt more than 800 meters belowground. For the next year they are monitoringhow quickly and extensively those carlbonate crystals appear. Some scientistshave presumed that the process takes millennia t occur naturally, but laboratoryresults suggest it can occur in less than a decade.“It's not 1,000 yesrs-it'snot even several centuries," says Pete McGrai, an environmental engineer aPacific Norlhwest National Laboratory, which oversees the project. “We’re talking a fewyears to a few decades to complete the minralization." That is quickenough to make a difference in the fight against global warming. Researchersexpect to know more in December, when they have their first drillsamples.
Engineers at a second project in Iceland,known as CarbFix, are injecting 1,500 tons of CO2 over two years.They plan to pull samples in May and June 2014 and will continue monitoring throughnext December, according to Juerg Matter, a researcher at Columbia Universitywho is involved with the work.
Some scientists are skeptical aboutwhether the carbonate minerals are as leak-proof as hoped. Susan Hovorka, ageologist and carbon-sequestration expert at the University of Texas at Ausin,says in certain conditions water deep below the surface could flow across thecarbonate crystals and dissolve out the CO2, allowing the gas topossibly seep to the surfacc. Testing will be needed, she notes, to determinehow well basalt will retain the carbon.
The primary obstacle to carbon storage ispolicy rather than technical know-how, McGrail says Without some economicincentive to sequester CO2 in this (or any) fashion, the practice isunlikcly to spread.Still, if the pilot projects offer proof that the gas can belocked underground and policy makers follow with a tax on carbon, basalts couldprovide a viable storage option. About a quarter of India's many coal-firedpower plants sit atop a huge basaltic formation known as the Deccan Traps. Ifbasalt can put our global warming villain back ftom whence it came, there's awhole lot of CO2 ready to lock.
All the folowing words in the passage refer to the same thing EXCEPT_________
A、sequester
B、lock
C、inject
D、entomb
【正确答案】：C